By the time the pilot arrives, the airplane has already undergone a series of checks by ANA's highly trained professional mechanics. In the first check of the day, the mechanics turn on the power in the airplane and check that every system is operating correctly. They check that the hydraulic system works correctly, see that the rudder and ailerons move smoothly, and make sure that the tires are correctly pressurized.
Preparation during the winter is particularly thorough. Snow on the airplane affects more than just the weight of the plane -- it has a negative influence on its aerodynamic performance. While you are waiting to board, mechanics and other ground staff remove the snow from the aircraft. We have various methods of snow removal available to us today. Instead of removing it by hand, a chemical de-icing agent is sprayed on the aircraft to remove the snow. However, snow trapped in tight spots and places that can't be reached by the spray must be removed by hand, just like in the old days.
Summer also raises some concerns. After landing on a hot runway, a plane's tires become extremely hot. If the tires become too hot, the air pressure in the tire increases and air is released through the pressure release valve. That must be kept in mind when the aircraft tires are checked.